Opportunity knocked by Martian rock

Mars rover Opportunity has ground to a halt on the Red Planet's surface after failing to drill into an interesting-looking rock. NASA scientists will run tests today to investigate the problem.

The drilling target, known as Flat Rock, was not even scratched when the rover tried to bore out a sample. All its tools appear to be working well, according to the Nasa/JPL website, so the team will have another go on Sol 44 (the 44th Martian day of the mission).

While they wait, the scientists will try to analyse the rock using an alpha particle X-ray spectrometer. Opportunity will put the sensor against the rock overnight, and should get a breakdown of the its chemical make-up.

While the NASA teams get on with the serious science, and both rovers report positive indications that water flowed on the surface of the planet, the black helicopter brigade gets on with the business of spurious sightings.

Since the rovers began sending pictures back, helpful members of the public have been calling and emailing NASA with news of their discoveries. The Arizona Republic reports a bewildering variety of finds: a white bunny, stone tools, plants and letters of the alphabet have all been reported to NASA.

A New Jersey resident, George Filer, told the publication that he had spotted letters similar to E and G written on Martian rocks. His attempts to alert NASA have (so far) failed. A member of MUFON (Mutual UFO Network), Mr. Filer believes these letters were written by sentient beings. "They keep a lot from the public," he said.